Wear nature of cutting hard alloy tools with optimal diffusion polycarbide coatings

This article is devoted to the issue of wear of hard alloy cutters with optimal multicomponent diffusion carbide layers based on their structural studies. The formation of these carbide coatings on the hard alloy was carried out in two stages: 1) preliminarily prepared saturating powder mixture by aluminothermic synthesis of metals from oxides in the composition: 98 % (50 % Al2O3 + 50 % (70 % MexOy + 30 % Al)) + 2 % NH4Cl, where MexOy = oxides Cr2O3, TiO2, MoO3, V2O5, Nb2O5; 2) then thermal diffusion treatment of the hard alloy T15K6 (79 % WC + 15 % TiC + 6 % Co) in this saturating mixture at 1100 °C for 6 hours. Structural-phase and chemical analyzes of Cr-Ti—Mo and Cr—V—Nb carbide layers of optimal composition were carried out, when the hard alloy get maximum microhardness and wear resistance. It has been shown that when turning steel 40X (0.4 % C, 1 % Cr), the wear of cutters made of hard alloy T15K6 with optimal Cr—Ti—Mo and Cr—V—Nb carbide coatings is of a diffusion, adhesive and oxidative nature with the dominance of diffusion component. As a result of applying diffusion polycarbide coatings, the durability of hard alloy cutters and mills increased by 1.5—20 times compared with the traditional ones.